Singh Vandana, Tiwari Stuti, Sharma Ajit Kumar, Sanghi Rashmi
Department of Chemistry, University of Allahabad, Allahabad 211001, India.
J Colloid Interface Sci. 2007 Dec 15;316(2):224-32. doi: 10.1016/j.jcis.2007.07.061. Epub 2007 Jul 31.
Using persulfate/ascorbic acid redox system, a series of Cassia grandis seed gum-graft-poly(methylmethacrylate) samples were synthesized. The copolymer samples were evaluated for lead(II) removal from the aqueous solutions where the sorption capacities were found proportional to the grafting extent. The conditions for the sorption were optimized using copolymer sample of highest percent grafting. The sorption was found pH and concentration dependent, pH 2.0 being the optimum value. Adsorption of lead by the grafted seed gum followed a pseudo-second-order kinetics with a rate constant of 4.64 x 10(-5) g/mg/min. The equilibrium data followed the Langmuir isotherm model with maximum sorption capacity of 126.58 mg/g. The influence of electrolytes NaCl, Na(2)SO(4) on lead uptake was also studied. Desorption with 2 N HCl could elute 76% of the lead ions from the lead-loaded copolymer. The regeneration experiments revealed that the copolymer could be successfully reused for at least four cycles though there was a successive loss in lead sorption capacity with every cycle. The adsorbent was also evaluated for Pb(II) removal from battery waste-water containing 2166 mg/L Pb(II). From 1000 times diluted waste water, 86.1% Pb(II) could be removed using 0.05 g/20 ml adsorbent dose, while 0.5 g/20 ml adsorbent dose was capable of removing 60.29% Pb from 10 times diluted waste water. Optimum Pb(II) binding under highly acidic conditions indicated that there was a significant contribution of nonelectrostatic interactions in the adsorption process. A possible mechanism for the adsorption has been discussed.
采用过硫酸盐/抗坏血酸氧化还原体系，合成了一系列决明子种子胶接枝聚（甲基丙烯酸甲酯）样品。对共聚物样品进行了从水溶液中去除铅（II）的评估，发现其吸附容量与接枝程度成正比。使用接枝率最高的共聚物样品优化了吸附条件。发现吸附取决于pH值和浓度，最佳pH值为2.0。接枝种子胶对铅的吸附遵循准二级动力学，速率常数为4.64×10^(-5) g/mg/min。平衡数据遵循朗缪尔等温线模型，最大吸附容量为126.58 mg/g。还研究了电解质NaCl、Na₂SO₄对铅吸收的影响。用2N HCl解吸可从负载铅的共聚物中洗脱76%的铅离子。再生实验表明，尽管每循环一次铅吸附容量都会连续下降，但该共聚物至少可成功重复使用四个循环。还评估了该吸附剂对含2166 mg/L Pb(II)的电池废水中Pb(II)的去除效果。对于稀释1000倍的废水，使用0.05 g/20 ml的吸附剂剂量可去除86.1%的Pb(II)，而对于稀释10倍的废水，0.5 g/20 ml的吸附剂剂量能够去除60.29%的Pb。在高酸性条件下最佳的Pb(II)结合表明，吸附过程中非静电相互作用有显著贡献。讨论了一种可能的吸附机制。
